diff --git a/.rspec b/.rspec
index 83e16f8..a472683 100644
--- a/.rspec
+++ b/.rspec
@@ -1,2 +1,3 @@
 --color
 --require spec_helper
+--require rails_helper
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index c7cc410..27bab4f 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -12,12 +12,12 @@ class ApplicationController < ActionController::Base
   end
 
   def current_client
-    @current_client ||= Client.find_by key: request.headers["X-API-KEY"]
+    @current_client ||= Client.find_by key: request.headers["X_API_KEY"]
   end
 
   def current_ability
     @current_ability ||=
       current_client.try { |c| ClientAbility.new(c) } ||
-      Ability.new(current_user)
+      UserAbility.new(current_user)
   end
 end
diff --git a/app/controllers/transactions_controller.rb b/app/controllers/transactions_controller.rb
index a547d98..fd867a4 100644
--- a/app/controllers/transactions_controller.rb
+++ b/app/controllers/transactions_controller.rb
@@ -1,10 +1,12 @@
 class TransactionsController < ApplicationController
-  load_and_authorize_resource
   skip_before_filter :verify_authenticity_token, only: :create
 
   before_action :authenticate_user!, except: :create
   before_action :authenticate_user_or_client!, only: :create
 
+  # This line MUST be placed after authentication
+  load_and_authorize_resource
+
   def index
     gridparams = params[:transactions_grid] || Hash.new
     gridparams = gridparams.merge(
diff --git a/app/models/client_ability.rb b/app/models/client_ability.rb
index 1f804eb..1a5dd66 100644
--- a/app/models/client_ability.rb
+++ b/app/models/client_ability.rb
@@ -1,4 +1,4 @@
-class Ability
+class ClientAbility
   include CanCan::Ability
 
   def initialize(client)
diff --git a/app/models/user.rb b/app/models/user.rb
index c5886cf..6e98824 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -12,6 +12,7 @@
 
 class User < ActiveRecord::Base
   devise :timeoutable, :omniauthable, :omniauth_providers => [:zeuswpi]
+
   has_many :incoming_transactions,
     class_name: 'Transaction', foreign_key: 'creditor_id'
   has_many :outgoing_transactions,
diff --git a/app/models/ability.rb b/app/models/user_ability.rb
similarity index 91%
rename from app/models/ability.rb
rename to app/models/user_ability.rb
index c3a4c81..47af0c8 100644
--- a/app/models/ability.rb
+++ b/app/models/user_ability.rb
@@ -1,4 +1,4 @@
-class Ability
+class UserAbility
   include CanCan::Ability
 
   def initialize(user)
diff --git a/spec/apis/transactions_controller_spec.rb b/spec/apis/transactions_controller_spec.rb
new file mode 100644
index 0000000..32c7eb2
--- /dev/null
+++ b/spec/apis/transactions_controller_spec.rb
@@ -0,0 +1,58 @@
+describe TransactionsController, type: :api do
+  before :each do
+    @debtor   = create :user
+    @creditor = create :user
+    @api_attributes = {
+      debtor:   @debtor.name,
+      creditor: @creditor.name,
+      message:  Faker::Lorem.sentence,
+      euros:    1,
+      cents:    25
+    }
+  end
+
+  def post_transaction(extra_attributes = {})
+    post '/transactions', { transaction: @api_attributes.merge(extra_attributes) },
+        { 'HTTP_ACCEPT' => "application/json", "X_API_KEY" => @key }
+  end
+
+  before :each do
+    @client = Client.create name: "Tap"
+    @key = @client.key
+  end
+
+  describe "Authentication" do
+    it "should require a client authentication key" do
+      post '/transactions'
+      expect(last_response.status).to eq(401)
+    end
+
+    it "should work with valid key" do
+      post_transaction
+      expect(last_response.status).to eq(201)
+    end
+  end
+
+  describe "successfull creating transaction" do
+    it "should create a transaction" do
+      expect { post_transaction }.to change { Transaction.count }.by(1)
+    end
+
+    it "should set issuer" do
+      post_transaction
+      @transaction = Transaction.last
+      expect(@transaction.issuer).to eq(@client)
+    end
+  end
+
+  describe "failed creating transaction" do
+    it "should create a transaction" do
+      expect { post_transaction(euros: -5) }.to change { Transaction.count }.by(0)
+    end
+
+    it "should give 402 status" do
+      post_transaction(euros: -4)
+      expect(last_response.status).to eq(422)
+    end
+  end
+end
diff --git a/spec/controllers/transactions_controller_spec.rb b/spec/controllers/transactions_controller_spec.rb
index e96cc51..3c6ced4 100644
--- a/spec/controllers/transactions_controller_spec.rb
+++ b/spec/controllers/transactions_controller_spec.rb
@@ -1,7 +1,4 @@
-require 'rails_helper'
-require 'spec_helper'
-
-RSpec.describe TransactionsController, type: :controller do
+describe TransactionsController, type: :controller do
   describe "creating transaction" do
     before :each do
       @debtor = create(:user)
@@ -22,7 +19,7 @@ RSpec.describe TransactionsController, type: :controller do
       end
 
       it "should create a new transaction" do
-        expect {post :create, @attributes}.to change {Transaction.count}.by(1)
+        expect { post :create, @attributes }.to change { Transaction.count }.by(1)
       end
 
       it "should set debtor" do
@@ -58,7 +55,7 @@ RSpec.describe TransactionsController, type: :controller do
       it "should be refused" do
         expect do
           post :create, transaction: attributes_for(:transaction, cents: -20)
-        end.not_to change {Transaction.count}
+        end.not_to change { Transaction.count }
       end
     end
 
@@ -71,7 +68,7 @@ RSpec.describe TransactionsController, type: :controller do
             euros: 10000000,
             message: 'DIT IS OVERVAL'
           }
-        end.not_to change {Transaction.count}
+        end.not_to change { Transaction.count }
       end
     end
   end
diff --git a/spec/controllers/users_controller_spec.rb b/spec/controllers/users_controller_spec.rb
index e2c3d3b..86d0660 100644
--- a/spec/controllers/users_controller_spec.rb
+++ b/spec/controllers/users_controller_spec.rb
@@ -1,5 +1,36 @@
-require 'rails_helper'
+describe UsersController, type: :controller do
+   before :each do
+     @user = create :penning
+     sign_in @user
+   end
 
-RSpec.describe UsersController, type: :controller do
+   describe 'GET show' do
+     before :each do
+       get :show, id: @user
+     end
 
+     it 'should be successful' do
+       expect(response).to render_template(:show)
+       expect(response).to have_http_status(200)
+     end
+
+     it 'should load the correct user' do
+       expect(assigns(:user)).to eq(@user)
+     end
+   end
+
+   describe 'GET index' do
+     before :each do
+       get :index
+     end
+
+     it 'should load an array of all users' do
+       expect(assigns(:users)).to eq([@user])
+     end
+
+     it 'should render the correct template' do
+       expect(response).to have_http_status(200)
+       expect(response).to render_template(:index)
+     end
+   end
 end
diff --git a/spec/factories/transactions.rb b/spec/factories/transactions.rb
index 716b419..71e7e00 100644
--- a/spec/factories/transactions.rb
+++ b/spec/factories/transactions.rb
@@ -18,7 +18,7 @@ FactoryGirl.define do
     association :debtor, factory: :user
     association :creditor, factory: :user
     issuer { debtor }
-    amount { rand(100) }
+    amount { 1 + rand(100) }
     message { Faker::Lorem.sentence }
   end
 end
diff --git a/spec/helpers/transactions_helper_spec.rb b/spec/helpers/transactions_helper_spec.rb
index 48c6c73..3b3e225 100644
--- a/spec/helpers/transactions_helper_spec.rb
+++ b/spec/helpers/transactions_helper_spec.rb
@@ -1,14 +1,2 @@
-require 'rails_helper'
-
-# Specs in this file have access to a helper object that includes
-# the TransactionsHelper. For example:
-#
-# describe TransactionsHelper do
-#   describe "string concat" do
-#     it "concats two strings with spaces" do
-#       expect(helper.concat_strings("this","that")).to eq("this that")
-#     end
-#   end
-# end
 RSpec.describe TransactionsHelper, type: :helper do
 end
diff --git a/spec/helpers/users_helper_spec.rb b/spec/helpers/users_helper_spec.rb
index 890768c..bb943ca 100644
--- a/spec/helpers/users_helper_spec.rb
+++ b/spec/helpers/users_helper_spec.rb
@@ -1,14 +1,2 @@
-require 'rails_helper'
-
-# Specs in this file have access to a helper object that includes
-# the UsersHelper. For example:
-#
-# describe UsersHelper do
-#   describe "string concat" do
-#     it "concats two strings with spaces" do
-#       expect(helper.concat_strings("this","that")).to eq("this that")
-#     end
-#   end
-# end
 RSpec.describe UsersHelper, type: :helper do
 end
diff --git a/spec/models/client_spec.rb b/spec/models/client_spec.rb
index 33e905f..d96c171 100644
--- a/spec/models/client_spec.rb
+++ b/spec/models/client_spec.rb
@@ -9,14 +9,20 @@
 #  updated_at :datetime         not null
 #
 
-require 'rails_helper'
-
-RSpec.describe Client, type: :model do
+describe Client, type: :model do
+  before :each do
+    @client = create :client
+  end
   it "should have a valid factory" do
-    expect(create(:client)).to be_valid
+    expect(@client).to be_valid
   end
 
   it "should generate a key" do
-    expect(create(:client).key).to be_present
+    expect(@client.key).to be_present
+  end
+
+  it "should have a unique name" do
+    client = build :client, name: @client.name
+    expect(client).to_not be_valid
   end
 end
diff --git a/spec/models/transaction_spec.rb b/spec/models/transaction_spec.rb
index d05aaf8..4cd2a8f 100644
--- a/spec/models/transaction_spec.rb
+++ b/spec/models/transaction_spec.rb
@@ -13,9 +13,7 @@
 #  updated_at  :datetime         not null
 #
 
-require 'rails_helper'
-
-RSpec.describe Transaction, type: :model do
+describe Transaction, type: :model do
   it "has a valid factory" do
     expect(create(:transaction)).to be_valid
   end
@@ -36,4 +34,20 @@ RSpec.describe Transaction, type: :model do
     end
   end
 
+  describe "amount" do
+    it "should be positive" do
+      expect(build :transaction, amount: -5).to_not be_valid
+    end
+
+    it "should not be 0" do
+      expect(build :transaction, amount: 0).to_not be_valid
+    end
+  end
+
+  describe "debtor/creditor" do
+    it "should be different" do
+      @user = create :user
+      expect(build :transaction, debtor: @user, creditor: @user).to_not be_valid
+    end
+  end
 end
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index cc98894..e188fc1 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -10,10 +10,17 @@
 #  updated_at :datetime         not null
 #
 
-require 'rails_helper'
+describe User, type: :model do
+  before :each do
+    @user = create :user
+  end
 
-RSpec.describe User, type: :model do
   it "has a valid factory" do
-    expect(create(:user)).to be_valid
+    expect(@user).to be_valid
+  end
+
+  it "has a unique name" do
+    user = build :user, name: @user.name
+    expect(user).to_not be_valid
   end
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 831f776..f3829a4 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -22,6 +22,11 @@ Coveralls.wear!('rails')
 # See http://rubydoc.info/gems/rspec-core/RSpec/Core/Configuration
 require 'factory_girl'
 require 'devise'
+
+Dir[File.join(File.dirname(__FILE__), 'support', '**', '*.rb')].each do |f|
+  require f
+end
+
 RSpec.configure do |config|
   config.include FactoryGirl::Syntax::Methods
   config.include Devise::TestHelpers, type: :controller
diff --git a/spec/support/api_helper.rb b/spec/support/api_helper.rb
new file mode 100644
index 0000000..b67d167
--- /dev/null
+++ b/spec/support/api_helper.rb
@@ -0,0 +1,11 @@
+module ApiHelper
+  include Rack::Test::Methods
+
+  def app
+    Rails.application
+  end
+end
+
+RSpec.configure do |config|
+  config.include ApiHelper, type: :api #apply to all spec for apis folder
+end